.( Loading Towers of Hanoi benchmark...) cr

\ The classical Towers of Hanoi benchmark

\ From W.P. Salman, O. Tisserand and B. Toulout, FORTH, Macmillan
\ pp. 120-121

variable moves

: copy ( x y z -- x y z x y z)
  >r 2dup r@ -rot r>
;

: dispose ( x y z -- )
  2drop drop
;

: edit ( d a n -- d a n)
  copy drop swap ." From: " . ." to: " . cr
;

: prepare-call ( d a n -- d a n d i n-1)
  copy -rot over + 6 swap - rot 1-
;

: prepare-return ( d a n -- d a n i a n-1)
  copy swap rot over + 6 swap - swap rot 1-
;

: verify-hanoi ( departure arrival number -- )
  dup
  if prepare-call recurse
    edit
    prepare-return recurse
  then
  dispose
;

: verify-towers    ( -- )
  1 3 4 verify-hanoi
;

: hanoi ( departure arrival number -- )
  dup
  if prepare-call recurse
    1 moves +!
    prepare-return recurse
  then
  dispose
;

: towers-of-hanoi ( -- )
  0 moves !
  1 3 14 hanoi
  moves @ 16383 0= abort" towers-of-hanoi: wrong result"
;

towers-of-hanoi
verify-towers